This invention relates to polyphenylene oligomers and polymers that display excellent toughness. The invention also relates to integrated circuit articles having good fracture toughness and made using polyphenylene dielectrics.
Polymer dielectrics may be used as insulating layers between various circuits and layers within circuits in microelectronic devices, such as integrated circuits, multichip modules, and laminated circuit boards. The microelectronics fabrication industry is moving toward smaller geometries in its devices to enable lower power and faster speeds. As the conductor lines become finer and more closely packed, the requirements of the dielectrics between such conductors become more stringent.
While polymer dielectrics often provide lower dielectric constants than inorganic dielectrics, such as silicon dioxide, they often present challenges to process integration during fabrication. For example, to replace silicon dioxide as a dielectric in integrated circuits, the dielectric must be able to withstand processing temperatures during metallization and annealing steps of the process. Preferably, the dielectric material should have a glass transition temperature greater than the processing temperature. The dielectric must also retain the desirable properties under device use conditions. For example, the dielectric should not absorb water which may cause an increase in the dielectric constant and potential corrosion of metal conductors.
WO 98/11149, incorporated herein by reference, discloses a dielectric polymer, which is the reaction product of a cyclopentadienone functional compound and an acetylene functional compound and is useful for microelectronics fabrication.
The inventors have discovered that an integrated circuit article requires a fracture toughness of greater than about 0.3 in order to withstand manufacturing processes. Thus, according to a first embodiment, the invention is an integrated circuit article comprising an active substrate containing transistors and a pattern of metal lines forming an electrical interconnect structure wherein the metal lines are at least partially separated by a polyphenylene material. This integrated circuit article has a fracture toughness as defined, for example, by the modified Edge Liftoff Test of greater than about 0.3, preferably greater than 0.32 MPa-m1/2. Fracture toughness refers to both the cohesive and adhesive toughness of the components of the article and all interfaces between those components.
By the term polyphenylene, we mean a material which comprises predominately aromatic rings directly bonded to other aromatic rings. These aromatic rings may be phenyl rings; substituted phenyl rings; fused aromatic systems such as naphthalene, anthracene, phenanthrene, fluorene, and the like; and substituted fused aromatic systems. There may be linking groups in the polyphenylene polymer chain, such as oxygen, sulfur, sulfones, sulfoxides, amines, phosphorous, silicon, aliphatic carbon groups, carbonyl, carboxylate, etc., separating some of these aromatic rings. Substituent groups on the aromatic rings may be essentially inert or may be reactive species which can further react and link two or more polyphenylene polymer chains together.
To obtain the desired adhesion and toughness, it is preferred that the glass transition temperature, Tg, of the cured polyphenylene composition be less than 465xc2x0 C., but preferably greater than 350xc2x0 C. in order to withstand processing temperatures. Thus, according to a second embodiment, this invention is a polyphenylene having a glass transition temperature of less than 465xc2x0 C., preferably less than 450xc2x0 C. and preferably greater than 350xc2x0 C., more preferably greater than 400xc2x0 C.